Crystal Structure and Microwave Dielectric Properties of an Ultralow‐Temperature‐Fired (AgBi) 0.5 WO 4 Ceramic

A new microwave dielectric (AgBi) 0.5 WO 4 ceramic with an ultralow firing temperature was prepared by the solid‐state reaction method. (AgBi) 0.5 WO 4 can be obtained as a dense single‐phase bulk material with a calcination temperature of 500 °C and sintering temperatures of ca. 580 °C. The material has a microwave relative permittivity of ca. 35.9, a Qf value of ca. 13000 GHz, and a negative temperature coefficient of –69 ppm/°C at 7.5 GHz. The crystal structure of (AgBi) 0.5 WO 4 was determined by a combination of X‐ray and transmission electron microscopy (TEM) diffraction analysis. The compound crystallizes in the monoclinic C 12/ m 1 (no. 12) space group with the lattice parameters a = 10.1330(8) Å, b = 11.0013(0) Å, c = 7.2756(4) Å, and β = 127.712(3)°. From an X‐ray diffraction analysis, the (Ag 0.5 Bi 0.5 )WO 4 ceramic reacts with silver after heat treatment at 560 °C to form new compounds, namely, Bi 2 WO 6 and Ag 2 WO 4 . However, the (AgBi) 0.5 WO 4 ceramic is chemically compatible with aluminum powder at 600 °C as an alternative cofired electrode material. All the results suggest that (AgBi) 0.5 WO 4 ceramic is a promising new candidate material for ultralow‐temperature cofired ceramic (ULTCC) technology.